1. Field of the Invention
This invention relates broadly to automatic chemical analysis devices and automated methods of chemical analysis. More particularly, it concerns the automatic testing of liquid samples sealed in glass ampoules to determine the content of a gas contained in the samples, e.g., the carbon dioxide content for determination of the carbon content of the liquid sample.
2. Description of the Prior Art
The testing of water samples to determine the carbon content is necessary in a number of different studies and activities, e.g., in limnology and oceanography studies. A variety of testing methods of this type exist, but one of the widely used procedures measures total carbon in a sample after it has been converted to carbon dioxide by wet chemistry methods (see Menzel and Vacarro; J. of Limnology and Oceanography, Vol. 9: 138-142; 1964).
In that wet chemistry method, inorganic carbon is first removed by purging the sample with purified oxygen. The sample is then sealed in a glass ampoule with potassium persulfate and heated to 175 deg. C. The ampoule contents are then analyzed by manually breaking off the top of the ampoule, bubbling nitrogen gas through it to expell CO.sub.2 which is then typically passed to a nondispersive infrared analyzer to measure the quantity of CO.sub.2. An analysis performed in this manner requires much manual handling of test items so it is very time consuming and tedious. Hence, there has existed a need for improvements in such type of chemical analysis so that the procedure can be automated to free the laboratory personnel for other duties.
The general concept of automated chemical analysis is not new (see U.S. Pat. No. 3,269,800). Also, it is known to use revolving turrets or carousels to move sample vails, test tubes, etc. seratium into position at a work station for the withdrawal of test portions, to perform tests at the station or the like (see U.S. Pat. No. 4,166,094). Moreover, automated chemical analyzers have been devised that utilize advanced electronic circuits to control movement of test elements, the flow of reagents, the performance of test steps, etc. (see U.S. Pat. No. 4,168,955). Particularly in the medical field there has been many innovations relating to automated chemical analysis equipment (see U.S. Pat. No. 3,883,305).
Notwithstanding all the research and development on automated chemical analysis, this present invention provides still further improvements on automated chemical analysis methods and automatic chemical analysis devices.